Filter with efficiently sealed end

ABSTRACT

A filter element has a resiliently compressible end cap at a first axial end sealing the filter and providing sealed engagement with a flow tube.

BACKGROUND AND SUMMARY

The invention relates to fluid filters, and more particularly toimproved sealing of the filter media end.

The invention arose during continuing development efforts relating tofilter elements having pleated filter media having a plurality of pleatsin a closed loop, typically annular, for example as shown in U.S. Pat.Nos. 6,149,700, 6,261,334, 6,391,076, 6,398,832, all incorporated hereinby reference. The closed loop pleated filter media has an outerperimeter defined by a plurality of outer pleat tips, and an innerperimeter defined by a plurality of inner pleat tips, and has a hollowinterior extending along a given axis. Fluid flows axially in the hollowinterior, before or after flow through the media, depending on whetherthe flow is inside-out or outside-in. The filter element has an openaxial end providing an axial flow passage therethrough along the axiscommunicating with the hollow interior.

The present invention relates to improved sealing of the pleat ends atthe open axial end of the filter element, including improvements in boththe effectiveness of the sealing and manufacturing efficiency for costreduction. The invention further relates to other filter media endsealing techniques.

BRIEF DESCRIPTION OF THE DRAWINGS Prior Art

FIG. 1 is taken from FIG. 1 of incorporated U.S. Pat. No. 6,149,700.

FIG. 2 is taken from FIG. 2 of the noted incorporated '700 patent and isa sectional view taken along line 2—2 of FIG. 1.

FIG. 3 illustrates prior art and shows the open axial end of a closedloop pleated media filter element prior to potting of the end cap.

FIG. 4 illustrates prior art and shows the open axial end of the filterelement of FIG. 3 after potting of the end cap.

FIG. 5 is taken from FIG. 11 of the incorporated '700 patent, and is aview of a mold for molding an end cap onto pleated filter media of afilter element.

FIG. 6 is taken from FIG. 10 of the incorporated '700 patent, and is aview like a portion of FIG. 2, and shows an alternate embodiment.

Present Invention

FIG. 7 is like FIG. 2 and shows the present invention.

FIG. 8 is like FIG. 3 and shows the present invention.

FIG. 9 is like FIG. 4 and shows the present invention.

FIG. 10 is like FIG. 5 and shows the present invention.

FIG. 11 is like FIG. 6 and shows the present invention.

FIG. 12 is like FIG. 7 and shows a further embodiment.

FIG. 13 is like FIG. 7 and shows a further embodiment.

FIG. 14 is like FIG. 9 and shows a further embodiment.

DETAILED DESCRIPTION OF THE INVENTION Prior Art

FIGS. 1 and 2 show a filter 20 including a filter element 22 containedwithin a housing 24. Filter element 22 is provided by pleated filtermedia 26, FIG. 2, having a plurality of pleats 28, FIGS. 3, 4, in aclosed loop, typically an annulus, having an outer perimeter 30 definedby a plurality of outer pleat tips 32, and an inner perimeter 34 definedby a plurality of inner pleat tips 36. The annular closed loop has ahollow interior 38 extending along an axis 40. Housing 24 is typicallycylindrical and is provided by housing sections 42 and 44 mounted toeach other in conventional manner such as by overcenter spring clip typeclamps such as 46, or in other suitable manner. The housing has an inlet50 admitting inlet fluid, such as air or liquid, radially and/ortangentially into annular space 52 within the housing around filterclement 22. Alternatively, the inlet may be at an axial end of thehousing, for example as in incorporated U.S. Pat. No. 6,391,076. Thehousing may include an interior dam or deflection surface 54 forblocking direct impact against filter element 22 and/or for directingflow, for example in a spiral or toroidal pattern. The fluid flowslaterally or radially inwardly through filter media 26 into hollowinterior 38, and then the clean fluid flows axially rightwardly in FIG.2 in hollow interior 38 along flow passage 56 as shown at arrows 58, 59.Alternatively or additionally, the fluid may flow axially through thefilter media as in the noted incorporated '076 patent.

Flow passage 56 extending along axis 40 circumscribes hollow interior 38and has a flow perimeter 60 greater than inner perimeter 34 defined byinner pleat tips 36, as described in the incorporated '700 patent. Flowperimeter 60 is less than outer perimeter 30 defined by outer pleat tips32. Inner perimeter 34 defines and bounds a first cross-sectional area.Flow perimeter 60 defines and bounds a second cross-sectional area. Thesecond cross-sectional area is greater than the first cross-sectionalarea. Outer perimeter 30 defines and bounds a third cross-sectionalarea. The second cross-sectional area is less than the thirdcross-sectional area. Filter element 22 has first and second axial ends62 and 64. Axial end 62 is open and provides axial flow passage 56therethrough. An end cap 66 of soft resilient compressible material,such as foamed potted urethane, axially abuts the axial ends 68 of thepleats. End cap 66 has an inner perimeter 70 greater than innerperimeter 34 defined by inner pleat tips 36. End cap 66 partially coversthe axial ends 68 of the pleats such that the laterally outward portions72 of the axial ends 68 of the pleats 28 are covered by end cap 66 butnot the laterally inward portions 74 of the axial ends 68 of the pleats,such that the laterally inward portions 74 of the axial ends of thepleats are uncovered and exposed at axial end 62 of filter element 22,FIG. 4.

In one embodiment, second axial end 64 of filter element 22 is closed. Asecond end cap 76, FIG. 2, of soft compressible resilient material, suchas foamed potted urethane, is provided at second end 64 of filterelement 22 and completely covers the axial ends 78 of the pleatsincluding the outer pleat tips 32 and the inner pleat tips 36 at axialend 64. End cap 76 also includes a central section 80 spanning andcompletely covering hollow interior 38 of filter element 22 at axial end64 of the filter element. Housing section 44 includes an annularinterior sidewall 82 extending partially axially into the housing tolocate and retain filter element 22 at axial end 64. In otherembodiments, central section 80 of end cap 76 is omitted, and a portionof housing 44 extends into hollow interior 38 of filter element 22 toclose axial end 64 of the filter element and to position axial end 64 ofthe filter element within the housing. Further embodiments are shown inthe noted incorporated '076 patent. End cap 76 includes an annular ridge84 engaging axial end wall 85 of housing section 44 and slightly axiallycompressed there-against to further aid in retention of filter element22 within the housing and to accommodate axial tolerances. End cap 66also includes an annular ridge 86 engaging axial end wall 88 of housingsection 42 and slightly radially compressed thereagainst to aid inretaining filter element 22 within the housing and to accommodate axialtolerances and also to provide an axial seal to prevent bypass of dirtyair from annular chamber 52 around axial end 62 of the filter element.Axial end wall 88 of housing section 42 has an outlet flow tube 90extending therethrough. In addition to or alternatively to the axialseal at 86, end cap 66 provides a radial seal at 70 against outlet flowtube 90.

End cap 66 has a sidewall 92 extending axially away from axial ends 68of pleats 28 at axial end 62 of filter element 22. The sidewall has thenoted inner perimeter 70, and has an outer perimeter 94. As noted above,inner perimeter 70 of sidewall 92 is greater than inner perimeter 34 offilter element 22 defined by inner pleat tips 36. Inner perimeter 70 ofsidewall 92 of end cap 66 is less than outer perimeter 30 of filterelement 22 defined by outer pleat tips 32. Outer perimeter 94 ofsidewall 92 of end cap 66 is greater than outer perimeter 30 of filterelement 22 defined by outer pleat tips 32. Flow tube 90 has an innersection 96 axially facing the axial ends 68 of pleats 28. Inner section96 of flow tube 90 has an inner perimeter 98 and an outer perimeter 100.Outer perimeter 100 is greater than inner perimeter 70 of sidewall 92 ofend cap 66, such that as filter element 22 at end cap 66 is axially slidrightwardly over inner section 96 of flow tube 90, end cap 66 isradially compressed to expand inner perimeter 70 along outer sidewall100 of flow tube inner section 96 to effect the noted radial seal. Innerperimeter 70 of end cap 66 is preferably stepped, as shown at 71 in FIG.8 of the noted incorporated '700 patent, to have slightly progressivelydecreasing diameters from right to left as viewed therein, to receiveand guide inner section 96 of flow tube 90 therealong and increaseradial sealing pressure. End cap 66 circumscribes inner section 96 offlow tube 90 and bears radially thereagainst at 70 in sealing relationto form the noted radial seal thereat. End wall 88 of housing section 42axially faces axial ends 68 of pleats 28, and end cap 66 also bearsaxially against end wall 88 in sealing relation at 86 to form the notedaxial seal thereat.

An outer liner 102, FIG. 2, provided by an expanded wire mesh or screenor perforated metal or plastic, circumscribes filter element 22 alongouter pleat tips 32 and has an axial end section 104 extending axiallybeyond the axial ends 68 of pleats 28. An inner liner may also beprovided at inner perimeter 34 along inner pleat tips 36. As abovedescribed, flow tube 90 communicates with hollow interior 38 of thefilter element along flow passage 56 and extends axially from the axialend of the filter element. End cap 66 at the axial end of the filterelement bears radially between and is radially compressed between andagainst section 104 of outer liner 102 and inner section 96 of flow tube90. Outer liner 102 extends axially at 104 into end cap 66 and is pottedtherein during the molding process, as described in the incorporated'700 patent. As noted above, sidewall 92 of end cap 66 extends axiallyaway from the axial ends 68 of pleats 28 at the axial end of the filterelement. Outer perimeter 94 of the end cap sidewall circumscribes outerliner section 104. The filter element may also include an inner liner103, FIG. 5, along inner pleat tips 36.

Pleats 28 have pairs of walls defining axially extending interiorchannels 106, FIG. 3, and also as shown in FIG. 7 of the incorporated'700 patent, and axially extending exterior channels 108. The walls ofthe pleats defining the exterior channels 108 are sealed to each othernear axial end 62 of the filter element by heat seal bonding along gluestrips, also known as hot melt, such as 110, and as shown in theincorporated '700 patent at FIGS. 4-6, 9, and for example as disclosedin U.S. Pat. No. 5,106,397, incorporated herein by reference. Thisprevents bypass of dirty air around the axial ends of the pleats atinner exposed portions 74. Fluid such as air flowing radially inwardlythrough the filter media as shown at 112, and as shown in theincorporated '700 patent at FIG. 4, or alternatively flowing axially asshown in the incorporated '076 patent at FIGS. 15, 16 thereof, must flowthrough the sidewalls of pleats 28 before such fluid can flow axiallythrough hollow interior 40 as shown at arrow 58 or axially through theinward portions 74 of the axial ends 68 of the pleats as shown at arrow59. Some of such air can flow axially rightwardly as shown at arrow 59axially along interior channels 106, and the balance of the aircontinues radially inwardly as shown at arrow 114, and as shown in theincorporated '700 patent in FIG. 4, and then flows axially as shown atarrow 58. The axial ends of exterior channels 108 at the axial end ofthe filter element are blocked by the noted hot melt seal bonding alongadhesive strips 110. Fluid flowing through the filter element is forcedto pass from exterior channels 108 to interior channels 106. FIGS. 6 and9 of the incorporated '700 patent show the seal bonded adhesive 110extending in exterior channels 108 all the way from inner pleat tips 36to outer pleat tips 32 as idealized. If the seal bond does not extendall the way from inner pleat tip 36 to outer pleat tip 32, then theshape of the interior channel 106 at outer pleat tip 32 will generallybe more rounded and the walls of pleats 28 forming exterior channels 108at outer pleat tips 32 will usually be closer together. In analternative, the adhesive seal bond in exterior channels 108 may extendfrom inner pleat tips 36 only partially towards outer pleat tips 32, andthe outer portions of exterior channels 108 are blocked at the axial endof the filter element at end cap 66. During the molding potting process,the liquid castable material into which the pleated filter media isdipped will foam up a short distance axially into the channels betweenthe pleats, as shown in the incorporated '700 patent at inner section116 in FIGS. 4, 8, 9 thereof, of the end cap which has migrated adistance 118, FIG. 4 of the incorporated '700 patent, between thepleats. The spacing of glue strips 110 on the pleats from the axial ends68 of the pleats may be adjusted as desired in standard glue seal stripapplicator machines. Preferably, glue seal strips 110 are spaced fromaxial ends 68 of the pleats by a small distance 118 to enable a slightdeformation of the axial ends 68 of the pleats by a dam in the moldduring the molding potting process, to keep the liquid castable materialof the end cap from flowing radially inwardly into inner portions 74 ofthe pleat ends which are desired to be exposed, which molding processand dam are disclosed in the noted '700 patent, and noted hereinafter.Alternatively, seal glue strips 110 may be applied at axial ends 68 ofthe pleats, without gap 118 therebetween.

FIG. 5 shows a mold 120 for molding or potting end cap 66 onto pleatedfilter media 26 of the filter element. The mold has a trough 122extending along an annular first perimeter and holding liquid castablematerial, such as urethane, therein into which axial ends 68 of pleats28 are dipped. The mold has an insert 124 with an upstanding dam 126extending along a second annular perimeter circumscribed by the notedannular perimeter of trough 122. Dam 126 engages axial ends 68 of thepleats between outer pleat tips 32 and inner pleat tips 36 and impedesflow of liquid castable material laterally radially inwardly towardsinner pleat tips 36. Trough 122 partially spans axial ends 68 of thepleats such that the laterally outward portions 72 of the axial ends ofthe pleats are covered by liquid castable material but not the laterallyinward portions 74 of the pleats, such that laterally outward portions72 of the axial ends 68 of the pleats are covered by end cap 66, and thelaterally inward portions 74 of the axial ends 68 of the pleats areuncovered by end cap 66 and are left exposed. It is preferred that thepleated filter media be dipped into the liquid castable material in themold by lowering the pleated filter media downwardly until axial ends 68of the pleats are engaged by dam 126, and then pushing the pleatedfilter media further slightly downwardly against the dam such that thedam slightly deforms axial ends 68 of the pleats at such engagementpoint which in turn pushes the pleat sidewalls forming the notedchannels slightly laterally to further block the channels and furtherimpede flow of liquid castable material laterally inwardly towards innerpleat tips 36. Trough 122 is bounded by an outer perimeter 126 and aninner perimeter 128. Outer perimeter 126 of trough 122 is greater thanouter perimeter 30 of the filter element defined by outer pleat tips 32.Inner perimeter 128 of trough 122 is less than outer perimeter 30 of thefilter element. Inner perimeter 128 of trough 122 is greater than innerperimeter 34 of the filter element defined by inner pleat tips 36. Thenoted second perimeter of the mold at annular dam 126 is less than orequal to inner perimeter 128 of trough 122.

As noted, the method for molding end cap 66 onto pleated filter media 26involves dipping axial ends 68 of the pleats into liquid castablematerial in trough 122 of mold 120, and engaging axial ends 68 of thepleats against dam 126 at a location between outer pleat tips 32 andinner pleat tips 36 such that dam 126 impedes flow of the liquidcastable material laterally inwardly towards inner pleat tips 36. Trough122 is provided and aligned such that it partially spans axial ends 68of the pleats such that the laterally outward portions 72 of the axialends of the pleats are covered by the liquid castable material duringdipping, but not the laterally inward portions 74 of the axial ends ofthe pleats. Further in accordance with the described method, laterallyinward flow of the liquid castable material is impeded along the axialends of the pleats toward inner pleat tips 36 by providing and aligningdam 126 to engage axial ends 68 of the pleats between outer pleat tips32 and inner pleat tips 36 such that laterally outward portions 72 ofthe axial ends of the pleats are covered by end cap 66, and laterallyinward portions 74 of the axial ends of the pleats are uncovered by endcap 66 and are left exposed. Trough 122 and filler element 22 arealigned during the noted dipping such that outer perimeter 126 of trough122 circumscribes outer perimeter 30 of the filter element defined byouter pleat tips 32, and inner perimeter 128 of trough 122 circumscribesinner perimeter 26 of the filter element defined by inner pleat tips 36.

FIG. 6 shows an alternate embodiment wherein outlet flow tube 90a has anouter section 90b of reduced diameter to accommodate engine compartmentsize and location requirements, yet maintaining an increased diameterinner section 90c maintaining the increased diameter and perimeter flowpassage 56 including axial fluid flow at 58 and the extra axial fluidflow at 59, FIGS. 2 and 6. The spacing of axial end wall 88 of housingsection 42 from axial ends 68 of the filter media pleats provides aplenum 130 accommodating the extra flow and reducing restriction.

The described filter construction was developed for air filters, thoughmay be used for other fluids such as liquid. In the disclosedembodiment, fluid to be filtered flows laterally inwardly through thefilter media from the outer perimeter to the inner perimeter and thenflows axially in the hollow interior, such that flow passage 56 is anoutlet flow passage. Alternatively, fluid to be filtered may flowaxially in hollow interior 38 and then flow laterally outwardly throughthe filter media from the inner perimeter to the outer perimeter, inwhich case flow passage 56 is the inlet flow passage. In anotheralternative, fluid flow to or from axial end 64 of the filter elementand through the media may be axial or a combination of axial and radial,for example as in the noted incorporated '076 patent. In otheralternatives, metal end caps are used instead of urethane end caps, orvarious combinations of materials are used for the end caps. In furtheralternatives, outer section 90b, FIG. 7, of the flow tube has a largerinner diameter than inner section 90c.

Present Invention

During further development, it has been found that there are someapplications where enhanced structural integrity is desired in the endcap area at 66, for example wet conditions, heavy load conditions,vibration, and the like. There are also circumstances where costreduction is desired. There are also circumstances where even furthersealing is desired.

FIGS. 7-11 are like FIGS. 2-6, respectively, and use like referencesnumerals where appropriate to facilitate understanding. Filter element22 is provided by pleated filter media 26 having a plurality of pleats28 in a closed loop having an outer perimeter 30 defined by a pluralityof outer pleat tips 32, and an inner perimeter 34 defined by a pluralityof inner pleat tips 36, and having a hollow interior 38 extending alongaxis 40. Fluid flows axially in hollow interior 38 as shown at arrow 58.The filter element has first and second axial ends 62 and 64. The firstaxial end is open and provides an axial flow passage 57 therethroughalong axis 40 communicating with hollow interior 38. A resilientlycompressible end cap 200 at the open axial end covers inner and outerpleat tips 36 and 32 and spans radially along axial ends 68 of thepleats between inner and outer perimeters 34 and 30. A flow tube 202communicates with hollow interior 38 and extends along axial flowpassage 57 and engages end cap 200. Flow tube 202 at engagement 204 withend cap 200 has an inner perimeter 206 greater than inner perimeter 34defined by inner pleat tips 36. Inner perimeter 206 of flow tube 202 atengagement 204 with end cap 200 is less than outer perimeter 30 definedby outer pleat tips 32. End cap 200 has a first section 208 extendingradially inwardly from outer perimeter 30 defined by outer pleat tips32, and has a second section 210 extending radially outwardly from innerperimeter 34 defined by inner pleat tips 36. First and second sections208 and 210 meet at a junction defining a step at 204 facing radiallyinwardly toward and engaging flow tube 202. The step at 204 has a firstaxial length. Flow tube 202 has an inner tubular portion 212 extendingaxially along step 204. Tubular portion 212 has an inner axial end 214facing the first axial end of the filter element at axial ends 68 of thepleats and separated therefrom by section 210 of end cap 200. Flow tube202 has a flange portion 216 extending radially from tubular portion 212and facing the first axial end of the filter element at axial ends 68 ofthe pleats and axially spaced from inner axial end 214 of tubularportion 212 by a second axial length which is less than the noted firstaxial length, to thus provide axial compression of end cap 200 includingat axial seal region 218. End cap 200 has a first axial thickness atfirst section 208 at outer perimeter 30, a second axial thickness atfirst section 208 at step 204, a third axial thickness at second section210 at step 204, and a fourth axial thickness at second section 210 atinner perimeter 34. The noted second axial thickness is greater than thenoted third axial thickness. The noted first axial thickness is greaterthan the noted fourth axial thickness. The noted first axial thicknessis less than the noted second axial thickness. The noted third andfourth axial thicknesses are substantially the same.

In one embodiment, the filter element includes in combination the notedsecond end cap 76 at the second axial end 64 of the filter element ataxial ends 78 of the pleats and covering inner and outer pleat tips 36and 32 and spanning radially between inner and outer perimeters 34 and30, and also spanning hollow interior 38 and closing the second axialend of the filter element. The filter element is preferably contained inthe noted housing having an end wall 220 facing the first axial end ofthe filter element. Flow tube 202 is part of end wall 220.

Flow tube 202 engages end cap 200 at first, second and third engagementseals 218, 222 and 224, respectively, to provide triple scaling of endcap 200 to flow tube 202. Seals 218 and 224 are axial seals, and seal222 is a radial seal. First inner portion 212 of flow tube 202 extendsaxially along step 204 and engages the step to form the noted secondradial seal 222. Tubular portion 212 has the noted inner axial end 214axially engaging end cap 200 at the noted second section 210 and formingthe noted third axial seal 224. Flow tube 202 has the noted flangeportion 216 extending radially from tubular 212 and axially spacedoutwardly of inner axial end 214 and axially engaging end cap 200 atfirst section 208 and providing the noted first axial seal 218. Secondradial seal 222 is axially between first and third axial seals 218 and224.

FIG. 10 shows a mold 120 for molding or potting end cap 200 onto pleatedfilter media 26 of the filter element. The mold has a trough 122 asabove. The mold has an insert 230 similar to insert 124 but withupstanding dam 232 at inner pleat tips 36 at inner perimeter 34.

FIG. 11 shows an alternate embodiment wherein outlet flow tube 202a hasan outer section 201a of reduced diameter to accommodate enginecompartment size and location requirements, yet maintaining an increasedinner diameter section 203a, as in FIG. 6. The spacing of axial end wall220 of the housing from axial ends 68 of the filter media pleatsprovides the noted plenum 130. End cap 200a has the noted first andsecond sections 208a and 210a. End cap 200a covers the inner and outerpleat tips 36 and 32 and spans radially between the inner and outerperimeters 34 and 30. The end cap provides the noted triple sealing ataxial seals 218a and 224a and at radial seal 222a.

As shown in comparing FIGS. 3, 4, 8, 9, the present construction sealsthe axial ends 68 of the pleats solely with urethane end cap 200, or200a, and eliminates reliance upon hot melt 110 for sealing purposes.This eliminates the adhesive component in the design of FIGS. 3, 4, andsimplifies the production process, reducing cost. In the presentconstruction of FIGS. 8, 9, the axial ends 68 of the pleats 28 aresealed with the same urethane 200, or 200a, used to pot the element,rather than a combination of hot melt 110 and urethane 66 as in FIGS. 3,4. The present construction also eliminates reliance upon the interfacebetween the glue 110, the filter media of the pleats 28, and theurethane 66 to prevent contaminants from passing to the clean side ofthe filter. The present construction further facilitates concentricityof the closed loop configuration. The present construction furtherenhances structural integrity, particularly in wet conditions, heavyload conditions, and vibration conditions.

FIG. 12 shows a further embodiment and uses like reference numerals fromabove where appropriate to facilitate understanding. End cap 200b hasfirst section 240 extending radially inwardly from the outer perimeter30 defined by outer pleat tips 32, and has a second section 242extending radially inwardly from first section 240. First and secondsections 240 and 242 meet at a junction defining a step 204b. Flow tube202b communicates with hollow interior 38 and extends along axial flowpassage 57. Flow tube 202b has an inner tubular portion 212b extendingalong step 204b and radially engaging the step to form a radial seal 222therewith. Flow tube 202b has the noted flange portion 216 extendingradially outwardly from tubular portion 212b and axially spaced fromfirst axial end 68 of the filter element by first section 240 of end cap200b therebetween. Flange portion 216 engages first section 240 of endcap 200b at engagement point 218b to form an axial seal therewith.Tubular portion 212b has an inner axial end 244 axially facing first end68 of the filter element. Second section 242 of end cap 200b is axiallybetween inner axial end 244 of tubular portion 212b and first axial end68 of the filter element. Second section 242 of end cap 200b extendsradially inwardly from first section 240 of the end cap all the way toinner perimeter 34 defined by inner pleat tips 36. End cap 200b coversinner and outer pleat tips 36 and 32 and spans radially between innerand outer perimeters 34 and 30. Inner axial end 244 of tubular portion212b is axially spaced from second section 242 of end cap 200b by anaxial gap 246 therebetween. This may be desired in some applications toprotect against excessive axial compression or axial crushing. Forexample, it may be desired to protect the pleat ends at 68 from the lineof axial force otherwise provided by the annulus at inner end 244 of theflow tube, with or without adhesive or hot melt 110 between the pleats.

FIG. 13 shows a further embodiment and uses like reference numerals fromabove where appropriate to facilitate understanding. End cap 200c has afirst section 250 extending radially inwardly from the outer perimeter30 defined by outer pleat tips 32, and has a second section 252extending radially inwardly from first section 250. First and secondsections 250 and 252 meet at a junction defining a step 204c. Flow tube202c communicates with hollow interior 38 and extends along axial flowpassage 57. Flow tube 202c has a tubular portion 212c extending axiallyalong step 204c and radially engaging the step to form a radial sealtherewith. Flow tube 202c has flange portion 216 extending radiallyoutwardly from tubular portion 212c and axially spaced from first axialend 68 of the filter element by the first section 250 of end cap 200ctherebetween. Flange portion 216 axially engages first section 250 ofend cap 200c at engagement point 218c to form an axial seal therewith.Tubular portion 212c has inner axial end 214 axially facing first end 68of the filter element. Second section 252 of end cap 200c is axiallybetween inner axial end 214 of tubular portion 212c and first end 68 ofthe filter element. Second section 252 of end cap 200c extends radiallyinwardly from first section 250 only partially towards inner perimeter34 defined by inner pleat tips 36 and does not cover inner pleat tips36. This embodiment may be desirable in instances where the additionalmigration or flow at 59 is desired. This embodiment may also bedesirable where additional flow of potting material into the pleat endsand between the wall segments of the pleats is desired. For example, thewider the radial extent of the end cap along axial end 68 of the filterelement, the greater the axially leftward migration of the moltenpotting material into and between the pleats. This may be desirable forenhanced sealing including greater interface area with the adhesive orhot melt 110 between the pleats. Inner axial end 214 of tubular portion212c may axially engage second section 252 of end cap 200c as shown inFIG. 13 to form a second axial seal 224 therewith as in FIG. 7.Alternatively, inner axial end 214 may be spaced axially rightwardly ofsecond section 252 of the end cap by an axial gap therebetween as ataxial gap 246 in FIG. 12.

FIG. 14 shows a further embodiment including a filter element 260including a closed loop filter media member 262 having a hollow interior264 extending along a given axis 266, and which may also include anouter prefilter member 268 such as open cell foam. Fluid flows axiallyin hollow interior 264. The filter element has first and second axialends 270 and 271. First axial end 270 is open and provides an axial flowpassage 272 therethrough along axis 266 communicating with hollowinterior 264. A resiliently compressible end cap 274 is provided atfirst axial end 270. A flow tube as shown in dashed line at 276 andwhich is comparable to flow tube 202, communicates with hollow interior264 and extends along axial flow passage 272. Flow tube 276 has atubular portion 278, comparable to tubular portion 212, engaging end cap274 and forming a seal therewith, comparable to seal 218 and/or 222and/or 224. Tubular portion 278 is cylindrical. Filter media member 262is non-cylindrical. In one embodiment, the filter media member iselliptical, such as oval, racetrack shaped, or the like. End cap 274 hasa first section 280 extending radially inwardly from an outer perimeter282, and has second section 284 extending radially inwardly from firstsection 280 to an inner perimeter 286. First and second sections 280 and284 are comparable to first and second sections 240 and 242 and to firstand second sections 250 and 252. First and second sections 280 and 284meet at a junction defining a step 288, comparable to steps 204, 204b,204c. First section 280 has the noted outer perimeter 282, and has aninner perimeter 290 at step 288. Second section 284 has an outerperimeter 292 at step 288, and has the noted inner perimeter 286communicating with hollow interior 264. Outer perimeter 282 of firstsection 280 is non-cylindrical. Inner perimeter 290 of first section 280is cylindrical. Step 288 is cylindrical. Outer perimeter 292 of secondsection 284 is cylindrical. Cylindrical tubular portion 278 engages endcap 274 at cylindrical step 288, comparable to the above notedengagement of cylindrical portions 212, 212b, 212c with steps 204, 204b,204c. Inner perimeter 286 of second section 284 is non-cylindrical.Filter media member 262 and outer perimeter 282 of first section 280 ofend cap 274 are elliptical and have a radially extending major axis(left-right in FIG. 14), and a radially extending minor axis (up/down inFIG. 14). The radial extension of first section 280 of end cap 274 alongthe major axis between outer perimeter 282 of first section 280 of endcap 274 and step 290 is greater than the radial extension of firstsection 280 of end cap 274 along the minor axis between outer perimeter282 of first section 280 of end cap 274 and step 288. The radialextension of second section 284 of end cap 274 along the minor axisbetween step 288 and inner perimeter 286 of second section 284 of endcap 274 is greater than the radial extension of the second section 284of end cap 274 along the major axis between step 288 and inner perimeter286 of second section 284 of end cap 274. In the embodiment shown,filter media member 262 is provided by pleated filter media having aplurality of pleats as above in a closed loop having an outer perimeterdefined by a plurality of outer pleat tips, comparable to pleat tips 32,and an inner perimeter defined by a plurality of inner pleat tips,comparable to pleat tips 36, the loop having the noted hollow interior264 extending along the noted given axis 266. Other types of filtermedia may be used, including non-pleated media. The disclosed ellipticalfilter design may be used in implementations where it is desired to havean elliptical filter and to maximize the inlet or outlet diameter of thefilter or match specifications requiring cylindrical inlet or outletflow tubes.

It is recognized that various equivalents, alternatives andmodifications are possible within the scope of the appended claims.

1. A filter element comprising pleated filter media having a pluralityof pleats in a closed loop having an outer perimeter defined by aplurality of outer pleat tips, and an inner perimeter defined by aplurality of inner pleat tips, said loop having a hollow interiorextending along a given axis, wherein fluid flows axially in said hollowinterior, said filter element having first and second axial ends, saidfirst axial end being open and providing an axial flow passagetherethrough along said axis communicating with said hollow interior, aresiliently compressible first end cap at said first axial end coveringsaid inner and outer pleat tips and spanning radially between said innerand outer perimeters, a flow tube communicating with said hollowinterior and extending along said axial flow passage and engaging saidend cap, wherein said flow tube at said engagement with said end cap hasan inner perimeter greater than said inner perimeter defined by saidinner pleat tips, and comprising in combination a second end cap at saidsecond axial end of said filter element covering said inner and outerpleat tips and spanning radially between said inner and outer perimetersand also spanning said hollow interior and closing said second axial endof said filterelement .
 2. The filter element according to claim 1 19wherein said inner perimeter of said flow tube at said engagement withsaid first end cap is less than said outer perimeter defined by saidouter pleat tips.
 3. The filter element according to claim 2 1 whereinsaid first end cap has a first section extending radially inwardly fromsaid outer perimeter defined by said outer pleat tips, and has a secondsection extending radially outwardly from said inner perimeter definedby said inner pleat tips, said first and second sections meeting at ajunction defining a stepfacing radially toward and engaging said flowtube .
 4. The filter element according to claim 3 20 wherein said stephas a first axial length, said flow tube has a tubular portion extendingaxially along said step, said tubular portion having an inner axial endaxially facing said first axial end of said filterelement , and saidflow tube has a flange portion extending radially from said tubularportion and facing said first axial end of said filter element andaxially spaced from said inner axial end of said tubular portion by asecond axial length less than said first said axial length.
 5. Thefilter element according to claim 3 wherein said first end cap has afirst axial thickness at said first section at said outer perimeterdefined by said outer pleat tips, a second axial thickness at said firstsection at said step, a third axial thickness at said second section atsaid step, and a fourth axial thickness at said second section at saidinner perimeter defined by said inner pleat tips, and wherein saidsecond axial thickness is greater than said third axial thickness. 6.The filter element according to claim 5 wherein said first axialthickness is greater than said fourth axial thickness.
 7. The filterelement according to claim 5 wherein said first axial thickness is lessthan said second axial thickness.
 8. The filter element according toclaim 5 wherein said third and fourth axial thicknesses aresubstantially the same.
 9. The filter element according to claim 1 19comprising a housing containing said filterelement , said housing havingan end wall axially facing said first axial end of said filterelement ,and wherein said flow tube is part of said end wall.
 10. The filterelement according to claim 1 wherein fluid flows laterally radiallythrough said filter element media between said outer and innerperimeters, and flows axially in said hollow interior.
 11. A filterelement comprising a closed loop filter media member having a hollowinterior extending along a given axis, wherein fluid flows axially insaid hollow interior, said filter element having first and second axialends, said first axial end being open and providing an axial flowpassage therethrough along said axis communicating with said hollowinterior, a resiliently compressible end cap at said first axial end, aflow tube communicating with said hollow interior and extending alongsaid axial flow passage, said flow tube having a tubular portionengaging said end cap and forming a seal therewith, said tubular portionbeing cylindrical, said filter media member being non-cylindrical. 12.The filter element according to claim 11 wherein said filter mediamember is elliptical.
 13. The filter element according to claim 11wherein said end cap has a first section extending radially inwardlyfrom an outer perimeter, and has a second section extending radiallyinwardly from said first section to an inner perimeter, said first andsecond sections meeting at a junction defining a step, said firstsection having said outer perimeter and having an inner perimeter atsaid step, said second section having an outer perimeter at said stepand having said inner perimeter communicating with said hollow interior,said outer perimeter of said first section being non-cylindrical, saidinner perimeter of said first section being cylindrical, said step beingcylindrical, said outer perimeter of said second section beingcylindrical.
 14. The filter element according to claim 13 wherein saidcylindrical tubular portion engages said end cap at said cylindricalstep.
 15. The filter element according to claim 13 further comprising aflow tube communicating with said hollow interior and extending alongsaid axial flow passage, said flow tube having a tubular portionengaging said end cap and forming a seal therewith, said tubular portionbeing cylindrical, wherein said inner perimeter of said second sectionis non-cylindrical.
 16. The filter element according to claim 13 whereinsaid filter media member and said outer perimeter of said first sectionof said end cap are elliptical and have a radially extending major axisand a radially extending minor axis, wherein the radial extension ofsaid first section of said end cap along said major axis between saidouter perimeter of said first section of said end cap and said step isgreater than the radial extension of said first section of said end capalong said minor axis between said outer perimeter of said first sectionof said end cap and said step, and wherein the radial extension of saidsecond section of said end cap along said minor axis between said stepand said inner perimeter of said second section of said end cap isgreater than the radial extension of said o second section of said endcap section along said major axis between said step and said innerperimeter of said second section of said end cap.
 17. The filter elementaccording to claim 11 wherein said filter media member comprises pleatedfilter media having a plurality of pleats in a closed loop having anouter perimeter defined by a plurality of outer pleat tips, and an innerperimeter defined by a plurality of inner pleat tips, said loop havingsaid hollow interior extending along said given axis.
 18. The filter ofclaim 1, wherein said first end cap is configured to receive a flow tubecommunicating with said hollow interior and extending along said axialflow passage and engaging said first end cap, wherein said flow tube atsaid engagement with said first end cap has an inner perimeter greaterthan said inner perimeter defined by said inner pleat tips.
 19. Thefilter of claim 1, further comprising a flow tube communicating withsaid hollow interior and extending along said axial flow passage andengaging said first end cap, wherein said flow tube at said engagementwith said first end cap has an inner perimeter greater than said innerperimeter defined by said inner pleat tips.
 20. The filter of claim 3,further comprising a flow tube communicating with said hollow interiorand extending along said axial flow passage and engaging said first endcap, wherein said flow tube at said engagement with said first end caphas an inner perimeter greater than said inner perimeter defined by saidinner pleat tips, the first and second sections meeting at a junctiondefining a step facing radially toward and engaging the flow tube. 21.The filter of claim 11, the end cap at said first axial end configuredto receive a flow tube communicating with said hollow interior andextending along said axial flow passage, said flow tube having a tubularportion engaging said end cap and forming a seal therewith, said tubularportion being cylindrical.
 22. The filter of claim 11 further comprisinga flow tube communicating with said hollow interior and extending alongsaid axial flow passage, said flow tube having a tubular portionengaging said end cap and forming a seal therewith, said tubular portionbeing cylindrical.
 23. A filter assembly comprising: a filter mediaelement comprising a first end and a second end, the element beingshaped to form a hollow interior extending from the first end to thesecond end, wherein the hollow interior defines an inner boundary of theelement and the outer surface of the element defines an outer boundary;a first end cap disposed at the first end; a second end cap disposed atthe second end, the second end cap covering both the filter element andthe hollow interior at the second end; and a step disposed on the firstend cap for reception of a flow tube, the step being a right angle.